Macrophage PET/CT Imaging Using 64Cu-DOTATATE for the Diagnosis of Cardiac Sarcoidosis

Cardiac involvement is considered a serious condition and a frequent cause of death in patients with sarcoidosis. 18F-FDG PET/CT is currently used as part of the diagnostic criteria for cardiac sarcoidosis, but it has shown limitations in the evaluation of cardiac sarcoidosis due to the high physiological uptake of FDG in normal cardiac muscle. Elaborate preparations are required for patients including either a low-carbohydrate diet followed by long fasting or heparin loading before FDG-PET. In heparin loading, the rare adverse effect of heparin-induced thrombocytopenia should be considered. Therefore, it is of interest to find a PET/CT tracer that displays high sensitivity and specificity without requiring thorough patient preparation and minimizing any adverse effects.

A potential tracer is the somatostatin-based tracer 64Cu-DOTATATE, which is routinely used for the diagnosis and monitoring of treatment response in patients with neuroendocrine tumors. Inflammatory cells, including macrophages that are found in sarcoid granulomas, express somatostatin receptors on their surface, whereas normal cardiomyocytes do not. This allows for the potential use of macrophage imaging in cardiac sarcoidosis.

In the CuDOSIS trial, groups A and B (suspected and confirmed cardiac sarcoidosis, respectively) will be scanned with 64Cu-DOTATATE PET/CT in addition to the routinely performed 18F-FDG PET/CT. Further, to examine whether the macrophage infiltration pattern is different in patients with cardiac sarcoidosis and other inflammatory heart diseases, a group of patients with confirmed or clinically suspected myocarditis will be included (group C); this group will only be scanned with 64Cu-DOTATATE PET/CT. Finally, data from a group of patients with neuroendocrine tumours (negative controls) who have previously been scanned with 64Cu-DOTATATE will be included.

Inclusion criteria

• Age => 18 years
• Group A: 22 patients with clinically suspected cardiac sarcoidosis Group B: 22 patients with known cardiac sarcoidosis Group C: Up to 10 patients with clinically suspected or confirmed acute lymphocytic myocarditis Group D: 22 patients with NET without known inflammatory heart disease who have previously been scanned with 64Cu-DOTATATE PET/CT as part of their routine diagnostic work-up or follow-up (control group)

Exclusion criteria

• Severe obesity (weight > 140 kg)
• Pregnancy (negative point-of-care urine/serum human chorion gonadotropin is required in all fertile women)
• Severe claustrophobia
• Known allergy to 64Cu-DOTATATE
• Clinically critical condition which makes PET/CT impossible
• Diabetes with insulin dependence